Translation of PCT/EP00/03271 as filed on Apr. 12, 2000.
The invention concerns a device for applying spatially limited elements, in particular, flexible elements, e.g. holograms or the like, to a continuous web which is removed from a supply roll and transported via a sealing station to a removal or guiding station, wherein the flexible element is applied to the continuous web in the sealing station.
Conventionally, cards, notes, paper sheets or the like are produced by initial processing of a continuous web through printing, punching, stamping etc., and finally cutting or punching out the individual products from the continuous web. Also conventionally, the individual products are provided with spatially limited elements, e.g. images or very expensive holograms and the like. These spatially limited elements are also disposed on a continuous web from which they are removed for disposal on the first continuous web. If the two continuous webs move through the sealing station at the same speed, only a fraction of the second continuous web is used and the major part of the second continuous web must be disposed of as waste, since the spatially limited element is substantially smaller than the products onto which they are to be applied. The intermediate spaces between the individual spatially limited elements on the second continuous web therefore constitute waste.
It is consequently the underlying purpose of the present invention to provide a device which improves utilization of the second continuous web to reduce waste.
This object is achieved in accordance with the invention in that, in a device of the above-mentioned type, two eccentric stations are provided, one before and one after the sealing station, wherein each eccentric station comprises an eccentric shaft via which the continuous web is guided, wherein the two eccentric shafts circulate, mutually offset by 180xc2x0.
Provision of an eccentric station before and after the sealing station through which the continuous web is guided permits deceleration and acceleration of the transport speed of the material web in these eccentric stations, which therefore act as a temporary buffer. This is effected by the eccentric shafts via which the continuous web is guided. As the eccentric shafts turn, they gather and subsequently release the continuous web during eccentric deflection. A sinusoidal reciprocating motion is thereby superimposed on the transport speed of the continuous web such that the resulting transport speed has slow and fast travel.
If the spatially limited element, e.g. the hologram is also located on a continuous web, the hologram is applied to the first continuous web, when the latter moves at its minimum transport speed. The continuous web carrying the holograms must therefore only be transported at this minimum transport speed and the waste between the individual holograms is accordingly reduced. After application of the hologram to the first continuous web, the latter is accelerated again to its maximum speed and subsequently decelerated for applying the next hologram.
The eccentric shafts preferably move in the transport direction of the continuous web thereby minimizing the relative speed and therefore the friction between eccentric shaft and the continuous web.
In a preferred embodiment, the eccentric shafts have a circular cross-section and are eccentrically mounted. A circular cross-section of the eccentric shaft advantageously has, in contrast to a cam-shaped eccentric shaft, a protective effect on the continuous web since the forces of the eccentric shaft acting on it increase and decrease in a sinusoidal fashion, thereby avoiding abrupt force peaks.
The frictional forces are reduced by disposing a sleeve on the eccentric shaft which can rotate with respect to the eccentric shaft and which has zero speed relative to the transported web.
In accordance with a preferred embodiment, the eccentricity of the eccentric shafts can be adjusted. The amplitude of the sinusoidal acceleration or deceleration can thereby be adjusted to a desired value.
In a further development, the eccentric shafts circulate synchronously with the application cycle. Every time sealing is to be effected, the continuous web moves at a minimum transport speed. This facilitates precise sealing and, during application, the first continuous web also has the same speed as the second continuous web from which the hologram is removed.
Further advantages, features and details of the invention can be extracted from the dependent claims and the following detailed description of a particularly preferred embodiment, with reference to the drawing. The features shown in the drawing and mentioned in the description and in the claims may be essential to the invention either individually or collectively in any arbitrary combination.